Method of manufacturing rods or wire of compound material having non-circular cross-section by hydrostatic extrusion

ABSTRACT

A wire or rod having an aluminum or aluminum alloy core and a copper or copper alloy casing is produced by hydrostatic extrusion of a compound billet through a die having a conical inlet with an outerpart with a cone angle between 70* and 115* and an inner part with a cone angle between 130* and 150*, the diameter of the inner part being substantially equal to the greatest dimension of the die opening.

Umted States Patent 1 1 1111 3,756,054 Hilsson 1451 Sept. 4, 1973 METHODOF MANUFACTURING RODS OR [56] References Cited WIRE OF COMPOUND MATERIALHAVING UNITED STATES PATENTS NON-CIRCULAR CROSS-SECTION BY 3,620,059 111971 Nilsson 72/60 HYDROSTATIC EXTRUSION 3,583,204 6/1971 Nilsson 72/467Inventor: Jan Nilsson, Robertsforsa Sw 2,218,459 /1940 Smger 72/467 [73]Assignee: Allmanna Svenska Elektriska Primary Examiner-Richard J. HerbstAtkiebolaget, Vasteras, Sweden Att0rney-Jennings Bailey, Jr.

1 [22] F1 ed Feb 7, 1972 ABSTRACT [21] Appl' 224,090 A wire or rodhaving an aluminum or aluminum alloy core and a copper or copper alloycasing is produced Foreign Application p i Data by hydrostatic extrusionof a compound billet through a die having a conical inlet with anouterpart with a Feb. 12, 1971 Sweden 1844/71 cone ang e bet ee and 1 5a an inner p with 52 vs. C]. 72/60, 72/467 8 3 angle between thediameter 51 1111. C1. B21c 3/10 "3 ""F subsemlally equal the greatest[58] Field of Search 72/60, 253, 467

6 Claims, 4 Drawing Figures I I A f 2 2 I r2 7 y I2 -u 2-: -/3 l 1 V T E8 1 0 Painted Sept. 4,1973

Fig

2 Sheets-Sheet 1 Patented Sept. 4, 1973 3,755,054

2 Sheets-Sheet 2 METHOD OF MANUFACTURING RODS OR WIRE OF COMPOUNDMATERIAL HAVING NON-CIRCULAR CROSS-SECTION BY HYDROSTATIC EXTRUSIONBACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to a method of manufacturing rods or wire havingnon-circular crosssection, from compound material having a core ofaluminum or an aluminum alloy and a casing of copper or a copper alloysurrounding the core, by means of hydrostatic extrusion.

2. The Prior Art It is known to use a compound billet for such anextrusion process formed of a core of aluminum and a casing of a coppertube surrounding the core. The billet is inserted in a pressure chambercontaining a pressure medium. Under influence of a high all-roundhydrostatic pressure, the billet is extruded through an opening in a dieand thus shaped to a product having the desired cross-section. In orderto join the core and the casing, they are sealed together at the rearend of the billet, for example with a sealing ring or a lid ofelastomeric material which prevents the pressure medium from penetratingbetween the core and the surrounding tube.

The prior applications of Burstrom, S.N. 32,195, filed Apr. 27, 1970 andNilsson, S.N. 758,308, filed Sept. 9, 1968 describe hydrostaticextrusion of compound products using a core of one material and a casingof another material. The die used for the extrusion process has aconical inlet opening. For hydrostatic extrusion the cone is normallyvery pointed, having a cone angle of about 45. The use of dies with suchpointed cones has produced satisfactory results when extrudinghomogenous material and if it is possible to perform the extrusion atrelatively low pressure. So far dies having relatively pointed cones,usually with a cone angle between 45 and 75, have been used forextruding compound material having an aluminum core and copper casing.

Wire or sections having non-circular cross-section, particularly havingrectangular crosssection and large side ratio, covered with a thincopper casing have been difficult to extrude. The material in the casingbecomes thicker on the short sides than on the long sides. The layerbecomes thinnest in the middle of the long sides and the material in thealuminum core may break through the copper layer.

SUMMARY OF THE INVENTION It has been found that the geometrical shape ofthe die has an enormous influence on the result of the extrusionprocess, particularly when the product being extruded has a rectangularcross-section. According to the invention, the inlet of the die hasinner and outer parts of differing cone angles, the angle of the innerpart being greater than that of the outer part. Better results areobtained by extruding wire or sections in a die having a double conicalinlet opening in accordance with the invention than by extrusion througha die having a conventional single-cone inlet opening, and sectionshaving smaller copper reduction area can be produced. The extrusion mustbe carried outwith an extrusion ratio exceeding 20, but it preferablyexceeds 50.

The extrusion ratio should preferably lie between and 250, but may be ashigh as 500.

The double conical inlet opening of the die should be shaped so that theouter, first conical part is more pointed than the inner, second conicalpart. The diameter at the transition between the conical parts of theinlet opening should be approximately equal to the greatest dimension ofthe die opening. For a rectangular extrusion opening, therefore, thediameter of the transition should be approximately equal to the diagonalof the rectangle. The angle of the first cone should be 70- and theangle of the second cone lS5. Particularly good results have beenachieved using angles of 7585 and l45, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described inmore detail with reference to the accompanying drawings.

FIG. 1 shows schematically a section through a pressure chamber duringextrusion of a billet,

FIG. 2 shows on a larger scale a view of the die from the inlet sideand;

FIGS. 3 and 4 sections through the die on the lines A-A and B-B of FIG.2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings 1 designates apress stand and 2 a pressure-generating plunger arranged in a hydraulicpress, not otherwise shown, in which there is a cylinder for operationof the plunger 2. The pressure chamber includes a high pressure cylinder3 constructed of a steel cylinder 4, a strip mantle 5 of rectangularhighstrength strip metal wound on under pre-stressing, and end pieces 6.Between the end pieces 6 and a spacer 7, sealing rings 8 and 9 arearranged to provide seals between the cylinder 4 and the extrusion die10 and the piston 2, respectively. In the pressure chamber is a billet11 comprising a core 12 of aluminum or an aluminum alloy and a casing 13of copper or a copper alloy surrounding the core. At the inner end ofthe billet there is an annular groove 14 in the core in which lies aring 15 which prevents the pressure medium 16 from penetrating betweenthe core and the casing. In this way the surfaces are kept free fromcontamination and a high pressure is obtained between the core and thecasing, which gives good adhesion. The adhesion can be further improvedby providing the core 12 with an additional groove 18. An extruded baris designated 17.

In FIGS. 2 4, 20 designates the double conical inlet opening. 21 is theouter, first conical part of the inlet opening and 22 its inner, secondconical part. The cone angles are designated a and I3 The rectangularextrusion opening is designated 23 and its diagonal D, the width B andthe height B. At the transition between the conical parts 21 and 22 thediameter is approximately equal to the diagonal D of the rectangle 23.The angle a should be 70l 15 and the angle B l25l55. Extremely goodresults have been obtained in dies having x= 80 and B= I claim:

1. Method of manufacturing rods or wire of compound material, havingnon-circular cross-section, with a core consisting essentially ofaluminum and a casing consisting essentially of copper surrounding thecore, by means of hydrostatically extruding a billet composed of a coreand a casing surrounding the core and sealed to the core at the rear endof the billet, which comprises inserting said billet in a pressurechamber and extruding the billet under the influence of a hydrostaticpressure in a pressure medium in the chamber surrounding the billetthrough a die with an opening shaped to the desired cross-section, thedie having a double conical inlet opening (20) and the outer, firstconical part (21) having a cone angle (a) between 70 and 1 and theinner, second conical part (22) having a cone angle (B) between 130 and150, the extruding ratio being greater than :1.

2. Method according to claim 1, in which the extrusion ratio is between50:1 and 500:1.

3. Die for hydrostatically extruding sections having noncircularcross-section and a core of aluminum and easing of copper the die (10)having a double conical inlet opening (20) and the outer, first conicalpart (21) having a cone angle (a) between and 1 15 and the inner, secondconical part (22) having a cone angle (B) between 130 and 150.

4. Die according to claim 3, in which the diameter at the transitionbetween the first and second conical parts (21,11) of the inlet opening(20) is approximately equal to the largest dimension D of the dieopening.

5. Die according to claim 3, in which the die opening (23) isrectangular and the diameter at the transition between the first andsecond conical parts (21, 22) of the inlet opening (20) is approximatelyequal to the length of the diagonal (D) of the die opening (23).

6. Die according to claim 3, in which the cone angle (a) of the firstconical part (21) is between and and the cone angle (B) of the secondconical part (22) is between and l45.

a: in s :r is

2. Method according to claim 1, in which the extrusion ratio is between50:1 and 500:1.
 3. Die for hydrostatically extruding sections havingnoncircular cross-section and a core of aluminum and casing of copperthe die (10) having a double conical inlet opening (20) and the outer,first conical part (21) having a cone angle ( Alpha ) between 70* and115* and the inner, second conical part (22) having a cone angle ( Beta) between 130* and 150* .
 4. Die according to claim 3, in which thediameter at the transition between the first and second conical parts(21,11) of the inlet opening (20) is approximately equal to the largestdimension D of the die opening.
 5. Die according to claim 3, in whichthe die opening (23) is rectangular and the diameter at the transitionbetween the first and second conical parts (21, 22) of the inlet opening(20) is approximately equal to the length of the diagonal (D) of the dieopening (23).
 6. Die according to claim 3, in which the cone angle (Alpha ) of the first conical part (21) is between 75* and 85* and thecone angle ( Beta ) of the second conical part (22) is between 135* and145* .